JP2009282292A - Protective agent for image carrier, protective layer forming device, image forming method, image forming apparatus, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that in an electrophotographic image forming apparatus, the average particle diameter of toner becomes smaller and the shape of the toner is more round, for responding to the request of high image quality, so that a blade for cleaning processing of residual toner requires stronger pressure and durability of the surface of an image carrier is adversely affected, thereby a solid lubricant is scraped by a supply member such as a brush, supplied to the surface of the image carrier, to be applied and form a uniform lubricant layer, but uniformization is difficult even when a uniformizing blade is used and failures such as the damage of the image carrier and wear of the uniformizing blade occur, because the size of the particles of the supplied lubricant is uneven. <P>SOLUTION: Wax used as a base material for a lubricant contains inorganic fine particles such as alumina fine particles. As the fine particles, ones having a circularity of from 0.40 to 0.80 are used, where it is defined as the circularity SR=the circumferential length of a circle having the same area as a particle projection area/the circumferential length of a particle projection image. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a protective agent for protecting the surface of an image carrier, in particular, an image carrier protective agent used for image formation using an electrophotographic system, and a protective layer forming apparatus for forming a protective layer with a protective agent on the surface of an image carrier The present invention relates to an image forming method using the image carrier protecting agent, an image forming apparatus having the protective layer forming apparatus, and a process cartridge.

Conventionally, in electrophotographic image formation, a latent image by an electrostatic charge is formed on an image carrier such as a photoconductive substance, and charged toner particles are attached to the electrostatic latent image to form a visible image. Forming. The visible image formed by the toner is finally transferred to a transfer medium such as paper, and then fixed to the transfer medium by heat, pressure, solvent gas, or the like, and becomes an output image.
These electrophotographic image forming apparatuses generally charge a drum-shaped or belt-shaped image carrier; generally a photoreceptor; while rotating it uniformly, and a latent image is formed on the image carrier by laser light or the like. A pattern is formed, which is visualized by a developing device, and further transferred onto a transfer medium.

Further, the toner component that has not been transferred remains on the image carrier after the toner image is transferred to the transfer medium. When these residues are conveyed to the charging process as they are, it is often the case that the uniform charging of the image carrier is hindered. The components and the like are removed in a cleaning process to make the surface of the image carrier sufficiently clean, and then charging is performed.
As described above, the surface of the image carrier is subjected to various physical stresses and electrical stresses in various processes such as charging, development, transfer, and cleaning, and the surface state changes as the usage time elapses.
Of these stresses, it is known that stress due to friction in the cleaning process causes the image carrier to wear and causes scratches.

  Further, the electrical stress on the image carrier in the charging process also greatly changes the state of the image carrier surface. This electrical stress is conspicuous in the contact charging method and the proximity charging method that involve a discharge phenomenon near the surface of the image carrier. In these charging methods, many active species and reaction products are generated on the surface of the image carrier, and many active species and reaction products generated in the atmosphere in the discharge region are adsorbed on the surface of the image carrier. For this reason, the adhesion force on the surface of the image carrier increases, the cleaning property deteriorates, and foreign matter adhesion (filming) is likely to occur. Furthermore, especially in the charging method in which the AC component is superimposed on the DC component, the influence on the material in the surface layer of the image carrier is large, and the molecular weight is reduced by the resin molecular chain breakage, the degree of entanglement of the polymer chain is reduced, and the resin is evaporated. Chemical degradation such as this occurs. Under such circumstances, if the surface of the image carrier is mechanically rubbed with a cleaning blade or the like, the wear of the image carrier is further promoted.

As described above, in recent electrophotographic systems, the problems of cleaning properties and photoconductor wear have become prominent, and it has become a major issue to achieve both these stably.
In order to solve such problems, various lubricants and lubricant component supply / films have been used so far to reduce the frictional force between the image carrier and the cleaning member and to suppress chemical deterioration of the image carrier surface. Many proposals have been made on forming methods (see, for example, Patent Documents 1, 2, 3, and 4).
Patent Documents 1 and 2 disclose solid lubricants such as zinc stearate as lubricants for reducing mechanical rubbing, and Patent Documents 3 and 4 disclose lubricants for protecting the photoreceptor surface from chemical deterioration. A configuration in which means for applying a lubricant is provided is disclosed.

Although these means exhibit an excellent effect for suppressing wear of the image carrier, a new problem that the lubricant itself passes through the cleaning blade and adheres to the charging member by using such means. There has occurred. If these substances adhere and accumulate on the charging member, they appear as abnormal images such as black stripes, which is not preferable.
Further, a lubricating component composed of a fatty acid metal salt (for example, see Patent Document 5) and a lubricant to which an abrasive composed of an inorganic compound powder is added (for example, see Patent Document 6) are disclosed. Yes.

However, these lubricants are effective in reducing scratches on the image carrier due to mechanical rubbing, but the effects of reducing electrical stress on the contact charging method and the proximity charging method and the contamination of the charging member are considered. Not.
In order to deal with the contamination of the charging member due to such a lubricant, there has been only a means for adjusting the amount of the lubricant applied so far, and it has been difficult to achieve both photoconductor wear and cleaning properties. In particular, in the form of the process cartridge, although the photosensitive member has a sufficient life, problems such as early replacement due to contamination of the charging member have occurred. At present, there are still few means for realizing long life.

The electrical stress in the charging process greatly changes the state of the image carrier surface. This electrical stress is conspicuous in the contact charging method and the proximity charging method that involve a discharge phenomenon near the surface of the image carrier. In these charging methods, many active species and reaction products are generated on the surface of the image carrier, and many active species and reactive organisms generated in the atmosphere in the discharge region are adsorbed on the surface of the image carrier. .
The lubricant using zinc stearate as in Patent Document 1 covers the surface of the image bearing member relatively evenly and gives good lubricity. Eventually, zinc oxide may remain on the surface of the image carrier or the surface of the charging member. Residual zinc oxide has hygroscopicity, and the resistance decreases due to moisture adsorption in the atmosphere, so it becomes impossible to retain the electrostatic charge on the image carrier in a high humidity environment, and the electrostatic latent image becomes obscured, A so-called blurred image, in which an image defect occurs, may occur.

In addition, the higher alcohol lubricant of Patent Document 2 easily wets the surface of the image carrier and can be expected to have an effect as a lubricant. However, the higher alcohol molecules adsorbed on the image carrier, the adsorption occupation area per molecule is Since the density of molecules adsorbed per unit area of the image carrier (adsorbed molecule weight) is small, the above-described electrical stress easily penetrates the protective layer, and the image carrier It is difficult to obtain an effect that sufficiently protects.
In addition, in a lubricant having a nitrogen atom in the molecule as in Patent Document 3, when the lubricant itself is subjected to the above-described electrical stress, ions similar to nitrogen oxides or ammonium-containing compounds as decomposition products A dissociative compound is generated and taken into the lubricating layer, and the lubricating layer may have a low resistance under high humidity, causing image blurring.

When a low-resistance material is taken into the lubricating layer in this way, to remove the low-resistance material, it is necessary to scrape the entire lubricating layer, for example, with a cleaning mechanism. In addition to requiring a large force, a large mechanical stress is applied to the image carrier at the time of removal, and an image carrier comprising a specific surface layer having a cross-linking structure as in Patent Document 4 is used. Even on the surface of the body, the life of the image carrier is not extended more than ever.
Further, in the cleaning of spherical toner represented by polymerized toner as in Patent Document 5 and Patent Document 6, proposals have been made to improve toner cleaning while reducing stress on the image carrier by the cleaning mechanism. However, it has not been improved at all in regard to extending the life in consideration of electrical stress on the image carrier.
As described above, protecting the surface of the image carrier from electrical stress in the charging step is an extremely important issue for extending the life of the image carrier and the charging member and stabilizing the image quality. However, it has been left as an important issue without sufficient consideration.

JP 2002-156877 A JP 2002-244516 A JP 2004-341480 A Japanese Patent Laying-Open No. 2005-115311 JP 2004-059882 A Japanese Patent Laying-Open No. 2005-091979

SUMMARY OF THE INVENTION The present invention provides an image carrier protecting agent that exhibits a sufficient protective effect on the surface of an image carrier, particularly a protective effect against stresses in a charging step and a cleaning step, in view of the above-described current problems. With the goal.
Another object of the present invention is to provide a protective layer forming apparatus for forming a good image carrier protective layer.
Another object of the present invention is to provide an image forming method and an image forming apparatus capable of stably obtaining an image of good quality over a long period of time.
It is another object of the present invention to provide a process cartridge capable of stably obtaining a good quality image.

According to the first aspect of the present invention, there is provided a protective agent for an image carrier that is applied to the surface of the image carrier to protect the surface of the image carrier, and the circularity SR = peripheral length of a circle having the same area as the particle projection area / Peripheral length of the projected particle image includes at least wax and fine particles having an average primary particle size of 0.1 μm or more and 2.0 μm or less and a circularity SR of 0.40 to 0.80. It is characterized by that.
According to a second aspect of the present invention, in the protective agent for an image carrier according to the first aspect, the fine particles are inorganic particles.

According to a third aspect of the present invention, in the protective agent for an image carrier according to the second aspect, the inorganic particles are alumina.
According to a fourth aspect of the present invention, in the protective agent for an image carrier according to any one of the first to third aspects, when the weight of the wax is A and the weight of the fine particles is B, the inclusion of the wax The amount is 20% by weight or more and 60% by weight or less based on the sum of A and B.

According to a fifth aspect of the present invention, there is provided a protective layer forming apparatus configured to be disposed close to an image carrier, wherein the protective agent supply is disposed on the surface of the image carrier so as to be able to supply a protective agent for the image carrier. 5. A member and a pressing force applying member that presses and contacts the protective agent for the image carrier against the protective agent supply member, and the protective agent for the image carrier is any one of claims 1 to 4. It is an image carrier protecting agent described in 1.
According to a sixth aspect of the present invention, in the protective layer forming apparatus according to the fifth aspect, when the apparatus is disposed close to the surface of the image carrier, the image carrier protective agent is supplied via the supply member. It supplies to the surface of an image carrier.

According to a seventh aspect of the present invention, an image carrier, an electrostatic latent image forming step for forming an electrostatic latent image on the surface of the image carrier, and developing the electrostatic latent image using toner may be used. A development process for forming a visual image, a transfer process for transferring the visible image to a recording medium, and an image carrier protective agent is applied or adhered to the surface of the image carrier after the toner image is transferred to the transfer medium. 5. The image forming method comprising a protective layer forming step for fixing and a fixing step for fixing the transferred image transferred to the recording medium, wherein the image carrier protective agent is according to claim 1. It is an image carrier protecting agent.
In the invention described in claim 8, the image carrier, the electrostatic latent image forming means for forming an electrostatic latent image on the surface of the image carrier, and the electrostatic latent image can be developed using toner. A developing means for forming a visual image, a transfer means for transferring the visible image to a recording medium, and an image carrier protecting agent is applied or adhered to the surface of the image carrier after the toner image is transferred to the transfer medium. 7. The protective layer forming apparatus according to claim 5, wherein the protective layer forming unit is a protective layer forming unit and a fixing unit that fixes the transferred image transferred onto the recording medium. It is characterized by that.
According to a ninth aspect of the present invention, there is provided the image forming apparatus according to the eighth aspect, wherein the image carrier is disposed downstream of the transfer unit and upstream of the protective layer forming unit with respect to a rotation direction of the image carrier. A cleaning device is provided for removing toner remaining on the surface of the body from the surface by rubbing against the image carrier.

According to a tenth aspect of the present invention, in the image forming apparatus according to the eighth or ninth aspect, the image forming apparatus further comprises a charging device disposed in contact with or close to the surface of the image carrier.
According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, the charging device includes a voltage applying device having an AC component.
According to a twelfth aspect of the present invention, there is provided a process cartridge which is configured to be detachable from the image forming apparatus main body and includes at least an image carrier and a protective layer forming means, wherein the protective layer forming means is the fifth aspect. Or it is the protective layer forming apparatus of 6.

According to a thirteenth aspect of the present invention, in the process cartridge according to the twelfth aspect, toner remaining on the surface of the image carrier is removed upstream of the protective layer forming means in the rotation direction of the image carrier. A cleaning means is provided.
According to a fourteenth aspect of the present invention, in the process cartridge according to the twelfth or thirteenth aspect, the process cartridge includes a charging device disposed in contact with or close to the surface of the image carrier.
In the invention described in claim 15, a process cartridge having an image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the surface of the image carrier, and the visible image are transferred to a recording medium. 15. An image forming apparatus having transfer means and fixing means for fixing a transfer image transferred to the recording medium, wherein the process cartridge is the process cartridge according to claim 12. Features.

  According to the present invention, the image bearing member is protected from electrical stress due to charging or the like and mechanical stress due to rubbing of the cleaning member, and the quality of the protective agent deteriorated by the electrical stress does not depend on the image quality or the image area. And an image carrier protecting agent that hardly affects the peripheral member and the peripheral member, a protective layer forming apparatus, an image forming method, an image forming apparatus, and a process cartridge using the same.

FIG. 1 is a schematic view of the construction of a protective layer forming apparatus used as a protective agent coating means of the present invention.
In the figure, reference numeral 1 is a photosensitive drum, 2 is a protective layer forming apparatus, 3 is 4 is an image carrier protective agent, 22 is a protective agent supply member, 23 is a protective agent stirring member, and 24 is a protective layer formation. A mechanism 25 indicates a protective agent container.
As a result of intensive studies, the present inventors have applied a protective agent thinly and uniformly on the image carrier and at the same time protected it by electrical stress in order to reduce the contamination of the charging member while protecting the image carrier. As a result of recognizing that it is an important issue to efficiently remove the agent and selecting an optimal material configuration to realize these states, the present invention has been achieved.
Hereinafter, the present invention will be described in more detail with reference to the drawings.
A protective layer forming apparatus 2 disposed opposite to the photosensitive drum 1 serving as an image carrier includes a powdery image carrier protective agent 21, a protective agent supply member 22, a protective agent stirring member 23, and a protective layer formation. It is mainly composed of a mechanism 24, a protective agent storage container 25, and the like.

The image carrier protecting agent 21 in the present invention is stirred by a protecting agent stirring member 23 and is pumped up to, for example, a brush-like protecting agent supply member 22. The protective agent supply member 22 rotates and rubs with the image carrier 1 with a linear velocity difference. At this time, the image carrier protective agent held on the surface of the protective agent supply member is supplied to the surface of the image carrier.
Since the image carrier protective agent supplied to the surface of the image carrier may not be a sufficient protective layer upon supply depending on the selection of the material type, for example, a blade-like member is used to form a more uniform protective layer. Is formed into a thin layer by the protective layer forming mechanism 24 having the above structure to form an image carrier protective layer.

In the present invention, at least the wax and fine particles having an average primary particle size of 0.1 μm or more and 2.0 μm or less are used as the image carrier protecting agent.
Examples of waxes used in the present invention include hydrocarbon waxes classified into aliphatic saturated hydrocarbons, aliphatic unsaturated hydrocarbons, alicyclic saturated hydrocarbons, alicyclic unsaturated hydrocarbons and aromatic hydrocarbons. Examples: Plant natural waxes such as carnauba wax, rice bran wax, and candelilla wax; and animal natural waxes such as beeswax and snow wax. These may be used individually by 1 type and may use 2 or more types together.
In particular, aliphatic saturated hydrocarbons and alicyclic saturated hydrocarbons, in which the intramolecular bond is composed of only a stable saturated bond with low reactivity, are preferred. Among them, normal paraffin, isoparaffin and cycloparaffin are less susceptible to addition reaction. Since it is chemically stable and hardly causes an oxidation reaction in the actual air, it is preferably used in terms of stability over time.

In particular, the use of a hydrocarbon wax containing at least one of Fischer-Tropsch wax and polyethylene wax as a relatively hard wax can increase the durability of the protective layer itself, and thus the protection formed on the surface of the image carrier. Since the protection of the image carrier can be realized without excessively increasing the thickness of the layer, it is more preferable.
Further, since the protective agent layer formed on the surface of the image carrier as described above is exposed to electrical stress and deteriorates, if the molecular weight of the wax is too small, a sufficient protective effect may not be exhibited.
On the other hand, if the molecular weight of the wax is too large, a large shearing force is required when forming the protective agent component for the image carrier on the image carrier, so that an equivalent protective film may not be formed.

  There are two main purposes to contain the fine particles, one is assistance for spreading the wax on the image carrier, and the other is deteriorated by being exposed to electrical stress after being applied on the image carrier. And the removal of discharge products incorporated in the wax. According to the study by the present inventors, for the purpose of removing the deteriorated wax and the discharge products incorporated in the wax, the action of fine particles such as toner and toner external additive is very large, The surface state of the image carrier changes depending on the presence or absence of these fine particle inputs. For this reason, for example, when a black belt image original is continuously fed, the image portion is almost free of wax deteriorated by fine particles such as toner and toner external additives, and discharge products incorporated in the wax. Is done. On the other hand, since the white part does not remove the wax and the discharge product taken in the wax, the ionic substance adheres to the image carrier, lowering the surface resistance and reducing the density. The fine particles of the image carrier protecting agent exert a function to remove the deteriorated wax and the discharge products taken into the wax, regardless of the image area.

FIG. 2 is a diagram showing the electrical conductivity of the protective layer according to the circularity of the alumina fine particles in the wax.
A protective layer forming apparatus in FIG. 1 is not used for charging, using an image carrier protective agent in which alumina fine particles having an average primary particle size of 0.3 μm and a circularity SR changed at a constant weight ratio are added. This is a result of measuring the electrical conductivity of the surface of the image carrier after rotating the image carrier while applying for 2 minutes, applying a charge, rotating it while applying for 5 minutes, and allowing it to stand for 20 minutes. In this experiment, the AC charging conditions were set to Vpp = 2.2 kV, f = 900 Hz, and Vdc = 0V. From this data, as the circularity SR is increased, the conductivity increases and becomes higher than the conductivity when the developer is added without the broken line protective agent. The allowable range is that the circularity SR is 0.8 or less, but when alumina fine particles having a shape lower than 0.4 were added, scratches were generated on the image carrier. The removal capability is limited by the scratches on the image carrier.

If the average primary particle size of the fine particles is larger than 2.0 μm, scratches are likely to occur when the surface of the image carrier is rubbed with a filler, and the amount of wear tends to increase. On the other hand, when the average primary particle size is less than 0.1 μm, the effect of spreading the protective agent on the surface of the image carrier is reduced, and the margin for filming is reduced.
Thus, the fine particles play an important role in uniformly applying the wax to the surface of the image carrier. By adding fine particles having an appropriate particle size range to the protective agent as in the present invention, the fine particles are always supplied to the surface of the image carrier, so that the wax application state is affected by the amount of toner input. It becomes difficult to form a uniform coating film.

  Typical examples of the organic fine particle material used in the present invention include a fluorine resin powder such as polytetrafluoroethylene, a silicone resin powder, a melamine resin powder, an acrylic resin powder, a polystyrene resin powder, and the like. Typical examples of materials include silica, tin oxide, zinc oxide, titanium oxide, alumina, zirconium oxide, indium oxide, antimony oxide, bismuth oxide, calcium oxide, cerium oxide, tin oxide doped with antimony and tin. Metal oxides such as indium oxide, metal fluorides such as tin fluoride, calcium fluoride, aluminum fluoride, metal titanium oxides such as potassium titanate, barium titanate, strontium titanate, mica, talc, kaolin, etc. Inorganic minerals, etc. The present invention is not limited to these N. In the present invention, the inorganic fine particles are more preferable because they have an advantageous effect on the removability of the protective agent, and alumina is particularly preferable because it exhibits the best action. These fine particles may be used alone or in combination of two or more. These fine particles may be subjected to a surface treatment with a surface treatment agent for the purpose of imparting hydrophobicity.

  Further, regarding the mixing ratio of the wax and fine particles, the content of the wax is in the range of 20 wt% or more and 60 wt% or less with respect to the sum of the weight (A) of the wax and the weight (B) of the fine particles. preferable. When the amount is less than 20% by weight, the function of the wax as a protective agent is insufficient, and the wear of the image carrier becomes remarkable. When the amount exceeds 60% by weight, the effect of the fine particles is weakened, so that the wax component is sufficiently spread on the image carrier. In other words, filming is likely to occur.

In the present invention, it is preferable to use a powdery protective agent obtained by mixing these materials. An example of a specific manufacturing method is given below.
1. Fine particles and, if necessary, a resin compatible with the wax are mixed in the heated and melted wax and sufficiently stirred with a stirrer or the like.
2. 1. The mixture is cooled and solidified.
3. 2. The solid protective agent is pulverized with a pulverizer and pulverized.
Through the above steps, the image carrier protecting agent of the present invention can be obtained.
In the present invention, if necessary, these powdery protective agents can be molded into a bar shape by compression molding or the like. In this case, a method is generally employed in which the bar is pressed against the protective agent supply member 22 using a pressure spring or the like, and the protective agent is supplied to the image carrier while the bar is being cut by the protective agent supply member 22.

The image carrier on which the protective layer is formed is formed by, for example, bringing a charging roller 3 to which a DC voltage or a voltage obtained by superimposing an AC voltage is applied with a high voltage power supply (not shown) into contact or in proximity, and discharging by a minute gap. The image carrier is charged. At this time, a part of the protective layer is decomposed or oxidized due to electrical stress, and air discharge products adhere to the surface of the protective layer.
The deteriorated image carrier protective agent is removed by the cleaning mechanism together with other components such as toner remaining on the image carrier by a normal cleaning mechanism. The cleaning mechanism may be combined with the protective layer forming mechanism described above, but the function of removing the image carrier surface residue and the function of forming the protective layer may differ in the rubbing state of an appropriate member. For this reason, it is preferable to provide a cleaning mechanism 4 including a cleaning member 41, a cleaning pressing mechanism 42, and the like on the upstream side of the image carrier protecting agent supply unit as shown in FIG.

  The material of the blade used for the protective layer forming mechanism is not particularly limited. For example, elastic materials such as urethane rubber, hydrin rubber, silicone rubber, and fluorine rubber, which are generally known as cleaning blade materials, may be used alone or in combination. Can be used. Further, these rubber blades may be coated or impregnated with a low friction coefficient material at the contact point with the image carrier. Further, in order to adjust the hardness of the elastic body, fillers represented by other organic fine particles and inorganic fine particles may be dispersed.

These blades are fixed to the blade support by an arbitrary method such as adhesion or fusion so that the tip can be pressed against the surface of the image carrier. The blade thickness cannot be uniquely defined in consideration of the force applied by pressing, but can be preferably used if it is about 0.5 to 5 mm, and more preferably about 1 to 3 mm.
Similarly, the length of the cleaning blade that protrudes from the support and can bend, that is, the so-called free length, is not uniquely defined in consideration of the force applied by pressing, but is generally 1 to 15 mm. If it is a grade, it can use preferably, and if it is about 2-10 mm, it can use still more preferably.

As another configuration of the blade member for forming the protective layer, the surface of the elastic metal blade such as a spring plate may be coated with a layer of resin, rubber, elastomer or the like via a coupling agent or a primer component, if necessary. It may be formed by a method, and if necessary, heat curing or the like may be performed, and if necessary, surface polishing or the like may be performed.
The thickness of the elastic metal blade is preferably about 0.05 to 3 mm, and more preferably about 0.1 to 1 mm.
Moreover, in an elastic metal blade, in order to suppress the twist of a blade, you may perform processes, such as a bending process, in the direction substantially parallel to a spindle after attachment.
As a material for forming the surface layer, fluorine resin such as PFA, PTFE, FEP, PVdF, silicone elastomer such as fluorine rubber, methylphenyl silicone elastomer, and the like can be used together with a filler, if necessary. It is not limited to this.

  Further, the force for pressing the image carrier by the protective layer forming mechanism is sufficient to spread the image carrier protective agent to become a protective layer or a protective film, and the linear pressure is 5 gf / cm or more and 80 gf / cm or less. It is preferable that it is 10 gf / cm or more and 60 gf / cm or less.

A brush-like member is preferably used as the protective agent supply member. In this case, the brush fiber is preferably flexible in order to suppress mechanical stress on the surface of the image carrier.
As a specific material of the flexible brush fiber, one or more kinds selected from generally known materials can be selected and used. Specifically, polyolefin resins (eg, polyethylene, polypropylene); polyvinyls and polyvinylidene resins (eg, polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and Polyvinyl chloride); vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; styrene-butadiene resin; fluororesin (eg, polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene); Polyester; Nylon; Acrylic; Rayon; Polyurethane; Polycarbonate; Phenol resin; Amino resin (eg urea-formaldehyde resin, mela Down resins, benzoguanamine resins, urea resins, polyamide resins); Among such, it may be a resin having flexibility.
Also, in order to adjust the degree of bending, diene rubber, styrene-butadiene rubber (SBR), ethylene propylene rubber, isoprene rubber, nitrile rubber, urethane rubber, silicone rubber, hydrin rubber, norbornene rubber, etc. are used in combination. Also good.

The support for the protective agent supply member includes a fixed mold and a rotatable roll. As a roll-shaped supply member, for example, there is a roll brush obtained by winding a tape made of brush fibers in a pile ground around a metal core bar in a spiral shape. The brush fiber has a fiber diameter of about 10 to 500 μm, the length of the brush fiber is 1 to 15 mm, and the brush density is 10,000 to 300,000 per square inch (1.5 × 10 ^{7 to} 4.5 × 10 per square meter). ^Eight ) are preferably used.

  For the protective agent supply member, it is preferable to use a material having a very high brush density from the viewpoint of supply uniformity and stability, and it is also possible to make one fiber from several to several hundred fine fibers. preferable. For example, bundling 50 fine fibers of 6.7 decitex (6 denier), such as 333 decitex = 6.7 decitex × 50 filament (300 denier = 6 denier × 50 filament), and implanting as one fiber Is also possible.

  Moreover, you may provide a coating layer in the brush surface for the purpose of stabilizing the surface shape of a brush, environmental stability, etc. as needed. As a component constituting the coating layer, it is preferable to use a coating layer component that can be deformed according to the bending of the brush fiber, and these are not limited as long as the material can maintain flexibility. Polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene, chlorosulfonated polyethylene, etc .; polystyrene, acrylic (for example, polymethyl methacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, Polyvinyl and polyvinylidene resins such as polyvinyl carbazole, polyvinyl ether, and polybiliketones; vinyl chloride-vinyl acetate copolymers; silicone resins composed of organosiloxane bonds or modified products thereof (for example, alkyd trees) , Polyester resins, epoxy resins, modified products such as polyurethane); fluorine resins such as perfluoroalkyl ether, polyfluorovinyl, polyfluorovinylidene, polychlorotrifluoroethylene; polyamide; polyester; polyurethane; polycarbonate; urea-formaldehyde resin, etc. Amino resins; epoxy resins and composite resins thereof.

FIG. 3 is a cross-sectional view for explaining a process cartridge using the protective layer forming apparatus of the present invention.
The image carrier 1 has a surface on which the image carrier protective agent, toner component, and the like partially deteriorated after the transfer process remain, but the surface residue is cleaned and cleaned by the cleaning member 41.
In the figure, the cleaning member is abutted at an angle similar to a so-called counter type (leading type).
The image carrier protective agent 21 is supplied from the protective agent supply member 22 to the surface of the image carrier from which the residual toner on the surface and the deteriorated image carrier protective agent have been removed by the cleaning mechanism. A film-like protective layer is formed. The image bearing member on which the protective layer is formed is charged, and then an electrostatic ray image is formed by exposure with a laser or the like, developed by the developing device 5 to be visualized, and transferred by the transfer roller 6 outside the process cartridge. Transferred to the medium 7.

FIG. 4 is a sectional view showing an example of an image forming apparatus provided with the protective layer forming apparatus of the present invention.
In the figure, reference numeral 100 denotes an image forming apparatus.
Around the drum-shaped image carrier 1, a protective layer forming device 2, a charging device 3, a latent image forming device 8, a developing device 5, a transfer device 6, and a cleaning device 4 are arranged. Done.

A series of processes for image formation will be described using a negative-positive process.
An image carrier 1 typified by a photoreceptor (OPC) having an organic photoconductive layer is neutralized by a neutralizing lamp (not shown) or the like, and is uniformly negatively charged by a charging device 3 having a charging member.
When the image carrier is charged by the charging device, an appropriate voltage or voltage suitable for charging the image carrier 1 to a desired potential from a voltage application mechanism (not shown) to the charging member. A charging voltage in which an AC voltage is superimposed on this is applied.
The charged image carrier 1 forms a latent image with laser light irradiated by a latent image forming device 8 such as a laser optical system (the absolute value of the exposed portion potential is lower than the absolute value of the non-exposed portion potential). ) Is performed.
Laser light is emitted from a semiconductor laser, and the surface of the image carrier 1 is scanned in the direction of the rotation axis of the image carrier 1 by a polygonal polygonal mirror (polygon) that rotates at high speed.
The latent image formed in this manner is developed with a developer composed of toner particles or a mixture of toner particles and carrier particles supplied onto a developing sleeve which is a developer carrying member in the developing device 5, and toner A visual image is formed.
At the time of developing the latent image, a predetermined voltage or an AC voltage is applied to the developing sleeve from a voltage application mechanism (not shown) between the exposed portion and the non-exposed portion of the image carrier 1. A superimposed developing bias is applied.

The toner image formed on the image carrier 1 corresponding to each color is transferred onto the intermediate transfer medium 7 by the transfer device 6 and is transferred onto the transfer medium such as paper fed from the paper feed mechanism 200. The image is transferred.
At this time, it is preferable that a potential having a polarity opposite to the polarity of toner charging is applied to the transfer device 6 as a transfer bias. Thereafter, the intermediate transfer medium 7 is separated from the image carrier 1 to obtain a transfer image.
The toner particles remaining on the image carrier are collected by the cleaning member 41 into the toner collecting chamber in the cleaning device 4.
As the image forming apparatus, an apparatus in which a plurality of the developing devices described above are arranged is used, and a plurality of toner images, which are sequentially produced by the plurality of developing devices, are sequentially transferred onto a transfer material, and then sent to a fixing mechanism to be heated. Even after a plurality of toner images produced in the same manner are sequentially transferred onto an intermediate transfer medium, and then transferred to a transfer medium such as paper in a batch. It is also possible to use a device that fixes the image.

The above-described charging device 3 may use any known configuration, but is more preferably a charging device disposed in contact with or close to the surface of the image carrier. This makes it possible to significantly suppress the amount of ozone generated during charging as compared to a so-called corotron or scorotron using a discharge wire.
However, in the charging device that charges the charging member in contact with or close to the surface of the image carrier, as described above, since the discharge is performed in the region near the surface of the image carrier, the electrical stress on the image carrier is large. It tends to be. By using the protective layer forming apparatus using the image carrier protecting agent of the present invention, the image carrier can be maintained for a long time without deteriorating. Fluctuations can be greatly suppressed, and stable image quality can be ensured.
Hereinafter, the present invention will be described in more detail with reference to examples, but the configuration of the present invention is not limited thereto. In the examples, all “parts” represent parts by weight.

The wax in the protective agent formulas 1 to 23 shown in Table 1 is put in a glass container with a lid and melted while stirring with a hot stirrer whose temperature is controlled to 120 ° C., then the fine particles in the protective agent formulations 1 to 23, A resin compatible with the wax was added, and the mixture was further stirred for 20 minutes.
Next, in order to fill the aluminum mold preheated to 85 ° C., each molten protective agent formulation composition is poured, allowed to cool to 50 ° C. in a room temperature atmosphere, and then set to 60 ° C. in a thermostatic bath whose temperature is set. And then kept at that temperature for 20 minutes, and then allowed to cool to room temperature.
After cooling, the protective agent solid was removed from the mold and pulverized into particles having a particle size of 100 μm or less by a pulverizer to obtain a powdery protective agent.
As described above, protective agents 1 to 19 that meet the specified range of the present invention and protective agents 20 to 23 that are outside the specified range of the present invention were produced.
The protective agent 22 was prepared by melting only wax and then cooling and pulverizing. The protective agent 23 was prepared by mixing fine particles and a fatty acid metal salt as they were with an Auster mixer.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example.

[Example 1]
A counter-type cleaning blade, a brush-like protective agent supply member, and a counter-blade type protective layer forming mechanism are provided in this order from the upstream around the image carrier (photoconductor) having an outer diameter of 40 mm following the transfer process. A process cartridge having a protective layer forming apparatus using the protective agent 1 of the protective agent production example 1 was prepared. Note that a hard resin roller having a diameter of 12 mm was used as the charging member, and the gap with the photosensitive member was adjusted to 50 μm.
This is mounted on a Ricoh color MFP image Neo Neo C3500 that has been modified so that the above process cartridge can be mounted, and the A4 version has an area ratio of 0, 25, 50, and 100%. A continuous paper passing test was conducted. As the charging condition, an alternating electric field in which a sinusoidal wave of Vpp = 3 kV and frequency = 1.5 kHz was superimposed as an AC component on a DC component of −600 V was applied. The presence or absence of image abnormality before and after the test was confirmed in a normal temperature and humidity environment of 20 ° C./50% RH, a low temperature and low humidity environment of 10 ° C./15% RH, and a high temperature and high humidity environment of 32 ° C./80% RH.

As image abnormalities, the presence or absence of streaky image defects, halftone image unevenness, background fogging, image blur, and other abnormalities related to the quality of cleaning performance was evaluated.
Further, in order to evaluate the magnitude of the influence of deterioration of the image carrier, the cleaning blade, and the charging member on the image, the respective states at the end of the continuous paper passing test were observed to check whether there was any abnormality.
In each member, there was no deterioration as the number of printed sheets increased, and good image quality was obtained at the initial stage after 100,000 sheets. The cleaning device and the image forming apparatus of the present invention were improved in image quality and lifetime. It turned out to be useful on both sides.
Tables 2 and 3 show the image quality evaluation results, and Table 4 shows the observation results of the member deterioration state. Each table includes the following examples and comparative examples.

The evaluation criteria in the above tables are as follows.
<Evaluation criteria for streak-like image defects>
◎: Extremely good ○: Practical problem level △: Practically acceptable level ×: Unusable

<Evaluation criteria for halftone image unevenness>
◎: Extremely good ○: Practical problem level △: Practically acceptable level ×: Unusable

<Evaluation criteria for image defects in blurred images>
◎: Extremely good ○: Practical problem level △: Practically acceptable level ×: Unusable

In addition, the presence or absence of foreign matter adhered to the surface of the image carrier protective agent at the time when 100,000 sheets were output was visually observed and evaluated according to the following criteria.
<Evaluation criteria for state of protective agent for image carrier>
◎: No sticking ○: Light sticking △: Scattered sticking (Available level)
×: Wide range of sticking

Furthermore, in order to evaluate the magnitude of the influence of image bearing member, cleaning blade, and charging member on the image, the state of each member is observed at the initial stage and when 100,000 sheets are output, and it is checked whether there is any abnormality. Confirmed and evaluated according to the following criteria.
<Evaluation criteria for the state of each member>
○: Level equivalent to the initial level Δ: Slightly changed (Actual usable level)
×: Deteriorated

[Examples 2 to 4]
Evaluation was performed in the same manner as in Example 1 except that protective agents 2 to 4 having different constituent materials were used as the protective agent.
Tables 2 and 3 show the image quality evaluation results, and Table 4 shows the observation results of the member deterioration state. The same applies to the following examples and comparative examples.
As in Example 1, each member did not deteriorate with an increase in the number of printed sheets, and good image quality was obtained both after the initial 100,000 sheets. The cleaning device and the image forming apparatus of the present invention were It was useful in terms of both image quality and lifetime.

[Examples 5 and 6]
In order to investigate the effect of using inorganic fine particles as a material, evaluation was performed in the same manner as in Example 1 except that protective agents 5 and 6 containing inorganic fine particles were used instead of protective agent 1 in Example 1.
As in Example 1, within the scope of the present invention, no deterioration was observed with each member under any conditions, and good image quality was obtained both initially and after 100,000 sheets. The cleaning device and the image forming apparatus of the present invention are useful in terms of both image quality and life.

[Example 7]
In order to investigate the effect of using alumina as a material, the protective agent 7 was used instead of the protective agent 1, and evaluation was performed in the same manner as in Example 1.
As in Example 1, within the scope of the present invention, no deterioration was observed with each member under any conditions, and good image quality was obtained both initially and after 100,000 sheets. The cleaning device and the image forming apparatus of the present invention are useful in terms of both image quality and life.

[Examples 8 to 10]
In order to examine the effect of defining the mixing ratio of the wax and the fine particles, the protective agent 8 to 10 was used instead of the protective agent 1, and evaluation was performed in the same manner as in Example 1.
There is no problem in Example 8. The wax contents of Examples 9 and 10 were 15 wt% and 70 wt% exceeding the range of 20 to 60 wt% which is the predetermined range of the present invention, but there was no particular problem except that filming occurred slightly. .

[Example 11]
A protective layer forming mechanism that also serves as a brush-type protective agent supply member and a counter type cleaning blade is provided in this order from the upstream around the image carrier having an outer diameter of 40 mm, following the transfer process. A process cartridge having a protective layer forming apparatus using the produced protective agent 7 was produced.
This is installed in the Ricoh color MFP image Neo Neo C3500 that has been modified so that the above process cartridge can be mounted, and the A4 version has an image area ratio of 0, 25, 50, and 100%. A continuous paper passing test was performed and the same evaluation as in Example 7 was performed.
As in Example 1, each member was good because no deterioration was observed as the number of drawn sheets increased.

[Comparative Examples 1-6]
In Example 1, instead of the protective agent 1, the same evaluation as in Example 1 was performed except that the protective agents 11 to 16 outside the specified range of the present invention were used.
The deterioration of the member was confirmed and an abnormal image was generated.

  Finally, the image forming apparatus of Example 1 was subsequently subjected to a paper passing test up to a total of 500,000 sheets, but no influence on the image was observed, and the image carrier, cleaning member, charging member, etc. Almost no deterioration was observed.

It is the schematic of the protective layer formation apparatus structure used as a protective agent application means of this invention. It is a figure which shows the electrical conductivity of the protective layer by the circularity of the alumina fine particle in wax. It is sectional drawing for demonstrating the process cartridge using the protective layer forming apparatus of this invention. It is sectional drawing which shows an example of the image forming apparatus which comprises the protective layer forming apparatus of this invention.

Explanation of symbols

1 Image carrier (photosensitive drum)
DESCRIPTION OF SYMBOLS 2 Protective layer formation apparatus 3 Charging roller 4 Cleaning mechanism 5 Developing apparatus 6 Transfer roller 7 Intermediate transfer body 8 Latent image forming apparatus 21 Image carrier protective agent 22 Protective agent supply member 23 Pressing force applying member 24 Protective layer forming member 25 Protection Agent storage container 41 Cleaning member 42 Cleaning pressing member 100 Image forming apparatus 200 Paper feed mechanism L Exposure

Claims (15)

  A protective agent for an image carrier that is applied to the surface of the image carrier to protect the surface of the image carrier, and the circularity SR = perimeter of a circle having the same area as the particle projection area / perimeter of the particle projection image When defined, for an image carrier comprising at least a wax and fine particles having an average primary particle size of 0.1 μm to 2.0 μm and a circularity SR of 0.40 to 0.80 Protective agent.   2. The protective agent for an image carrier according to claim 1, wherein the fine particles are inorganic particles.   The protective agent for an image carrier according to claim 2, wherein the inorganic particles are alumina.   The protective agent for an image carrier according to any one of claims 1 to 3, wherein when the weight of the wax is A and the weight of the fine particles is B, the content of the wax is the sum of A and B. A protective agent for an image carrier characterized by being 20 wt% or more and 60 wt% or less.   A protective layer forming apparatus configured to be disposed close to an image carrier, wherein the protective agent supply member is arranged to be able to supply a protective agent for the image carrier on the surface of the image carrier, and the protective agent supply member 5. The image carrier protecting agent according to claim 1, further comprising a pressing force applying member that presses and contacts the image carrier protecting agent, wherein the image carrier protecting agent is the image carrier protecting agent according to claim 1. There is provided a protective layer forming apparatus.   6. The protective layer forming apparatus according to claim 5, wherein when the apparatus is disposed close to the surface of the image carrier, the image carrier protective agent is supplied to the surface of the image carrier through a supply member. A protective layer forming apparatus.   An image carrier, an electrostatic latent image forming step of forming an electrostatic latent image on the surface of the image carrier, and a developing step of developing the electrostatic latent image with toner to form a visible image; A transfer step of transferring the visible image to a recording medium, a protective layer forming step of applying or adhering an image carrier protecting agent to the surface of the image carrier after the toner image is transferred to the transfer medium, and the recording 5. An image forming method comprising a fixing step of fixing a transferred image transferred to a medium, wherein the image carrier protective agent is the image carrier protective agent according to any one of claims 1 to 4. An image forming method.   An image carrier, an electrostatic latent image forming unit that forms an electrostatic latent image on the surface of the image carrier, and a developing unit that develops the electrostatic latent image with toner to form a visible image; Transfer means for transferring the visible image to a recording medium, protective layer forming means for applying or adhering an image carrier protective agent to the surface of the image carrier after the toner image is transferred to the transfer medium, and the recording 7. An image forming apparatus comprising: a fixing unit that fixes a transferred image transferred onto a medium. The image forming apparatus according to claim 5, wherein the protective layer forming unit is the protective layer forming apparatus according to claim 5.   9. The image forming apparatus according to claim 8, wherein the toner remaining on the surface of the image carrier is disposed downstream of the transfer unit and upstream of the protective layer forming unit with respect to the rotation direction of the image carrier. An image forming apparatus comprising: a cleaning device that removes from the surface by rubbing with an image carrier.   10. The image forming apparatus according to claim 8, further comprising a charging device disposed in contact with or in proximity to the surface of the image carrier.   The image forming apparatus according to claim 10, wherein the charging device includes a voltage applying device having an AC component.   7. A protective layer forming apparatus according to claim 5, wherein the process cartridge is configured to be detachable from the main body of the image forming apparatus and includes at least an image carrier and a protective layer forming unit. Process cartridge characterized by being.   13. The process cartridge according to claim 12, further comprising a cleaning unit that removes toner remaining on the surface of the image carrier on the upstream side of the protective layer forming unit with respect to the rotation direction of the image carrier. Process cartridge.   14. The process cartridge according to claim 12, further comprising a charging device disposed in contact with or close to the surface of the image carrier.   A process cartridge having an image carrier, an electrostatic latent image forming unit for forming an electrostatic latent image on the surface of the image carrier, a transfer unit for transferring the visible image to a recording medium, and a transfer to the recording medium 15. An image forming apparatus having fixing means for fixing the transferred image, wherein the process cartridge is the process cartridge according to claim 12.

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